5. Castle of Good Hope
The Castle of Good Hope is the oldest remaining colonial building in South Africa. It has witnessed the establishment of a very diverse and prosperous nation. The gigantic structure was constructed by the Dutch East India Company from 1666 to 1679. Located in Cape Town, the castle was declared a historical monument (now a provincial heritage site) in 1936. Part of the fort was used as a prison during the Second Boer War between 1899 and 1902.